Malcolm’s wife Annette issued a direct and emotional plea for his return, saying: “I just want you to know that I love you to bits,” but he has still not been found.

Malcolm, commonly known as Mac, left his home in Falklands Drive at about 6.30pm on Tuesday October 23, despite Annette pleading with him to stay in because it was dark.

“I didn’t want him to go as we never go out in the dark,” she said. “However he is a very strong and proud person and he was adamant that he needed to go for his walk. He was very determined and I couldn’t persuade him.”

Police have been looking for Mac ever since his disappearance, and have regularly visited Annette to comfort her and show her maps of where they have searched.

PC Lorna Owen, from Cambridgeshire Police’s missing persons department, said: “We are concerned about Malcolm because his disappearance is out of character.

“He left on foot with little money, no phone or extra clothing for cold weather and has made no contact with family or friends.”

Annette added: “It feels as if the house has had its heart ripped out of it. “I just want him to walk back in here and be at home with me.

“I never ever dreamt this would happen. It is so out of character.”

Annette has spent many nights since Mac’s disappearance sitting by the window of their home with the front door open in the hope he will walk back in.

Mac is described as white, 5ft 6in, slim, with light brown receding hair. He was wearing a grey jacket, black jumper and blue trousers.

One crew and rescue vehicle from Dogsthorpe, along with two Lincolnshire crews from Stamford and Market Deeping, were called to a road traffic collision on the A1 southbound between Carpenters Lodge and Wansford.